Injection pump assembly



Jal'l- 20, 1959 B. oxENFART ETAL 2,869,529

INJEcTxoN PUMP ASSEMBLY Filed sept. 7, 1955 ervold @Xenari' Lunch ldingel bu): maar@ 95mm aqt- INJECTION PUMP ASSEMBLY Berthold Oxenfart and Ulrich Aldinger, jStuttgart, Germany, assignors to Robert Bosch G.m. `b."H.,-Stutt gart, `Germany Application September 7, 1955,7Serial No. 532,959 `Claims priority, application Germany September 11,: 1954 12 Claims. .(Cl. 1231-140) `The present inventionyrelates tointernal combustion engines and more particularly to an injection pumprfor a multicylinder internal combustion engine-attritov the cooperation of such-an injection pump with avsupply pump for supplying fuel to the injection pump, witha governor for regulating the speed of the engine, and with a `.timer Afor timingtheoperation of the injectionj pump.

One. of the objects of the .present invention isto provide a single assembly which includes aninjection pump and a fuel supply pump therefor.

Another objectV ofthe present invention is to,y provide a single assembly which includes an injection pump,. a fuel supply pump therefor, anda timer for theinjection pump.

A further object of the present invention is toprovide a single assembly which includes an injection vpump and a governor.

An additional o-bject of the present invention isto provide a single assembly which includes an .injection pump,

.a fuel supply pump therefor, a timer. and agovernor.

Still another `object of the presentvinvention is to provide an assembly of the above type which is extremely compact, requires in its entirety but little .spa`ce,f.and which at the same time is inexpensive to manufacture. and very reliable in operation.

Furthermore, it is` an object of the-present invention to provide an assembly of theabove type which haseasily removable components, so that these components maybe removed and replaced by other components of different sizes, for example.

With the above objects in view the. present invention mainly consists of an assembly which includes an linjection pump and a supply pump, this assembly including a support means and a drive shaft turnably carriedvbyv the support means and forming part of a drive vto a ldistributor of the injection pump, thisV drive f shaft being formed with an axially extending Abore which actsa's` a cylinder of a supply pump for supplying fuel tothe injection pump. A piston is slidable in this bore,-and a transmission means cooperates withthe driver shaft and the piston for reciprocating the latter in the boreduring rotation of the drive shaft. I

The novel features which are considered as characteristic for the invention are set forth in particular `in Fig. 1 is a sectional elevational View of an assembly t `according to the present invention;

Fig. 2 is a fragmentary partly `sectional elevational View showing part of the structure'associatedwith the drive shaft in a plane different from that shown in Fig. 1; and

Fig. 3 is an elevationalv view of a member responsive Hited States ate-nt. r

" aslindicated in Fig. 1.

2,869,529 Patented Jan. 20, 1959 to `fuel pressureas seen in the directionfof the arrowflII ofFi'g. l.

The structure shown in the drawings is adapted to,be

supportmeans for. the various .elements of the structure ofthe invention. Thus, thehousingA v1carries a bearing sleeve 2 through which the drive 'shaft Broextends,4 so that in this way the .drive shaft 3 is supported. :for rotation about its axis. This drive shaft 3 is formed withan axially extending Vbore .4 which forms a cylinderpfga fuel supply` pumpand'a piston.5 slidesin .the,bor`e.,4. The drive shaft?) is formed with a passagev 6 communicating with. the bore4 vandapassing, through the. wallof the drive shaft 3. l i

o The bearing sleeve 2 Vis formed with, a-plurality ysf/:inlet openings 7 and outlet openings`8'all of whicharelocated in a common plane normal to the drive shaft axis, audit will benoted that the passage is also locatedg-in this plane so that during rotation of the drive. shaft 3 the bore 4will communicate throughthepassage with the several openings 7 and the several openings 8. 4Only one Vopening 7 and one opening S are shown in Eig. 1. The `openings 7 communicate with v an. outer annular groove 9 formed in the bearing, sleeve 2. This annular groove 9 communicates with a fuel inlet 10 formed. in theinjection pump housing. 1. The outlet openings; 8 communicate with the interiorspace 12 of the hollow housing` 1.

adjusting ,ring 15 is freely turnable on end portion 14 of the driveshaft 3 and engages one face of thegear55, The adjusting ring 15 turnably supports four rollers 16 which are respectively turnable about axes extending radiallyfrom thedrive shaft axis and which are spaced from each other by90 (Fig. 2'). A cam disc 18is provided withfour cammingjportions 17 spaced from each other by l90" and cooperating with the rollers 16 in the manner indicated in Fig. 2 ,ford `dis placing the cam disc 18 `axially during the rotation of this cam disc with respect to Vthe rollers 16. ,Thusthe rollers 16 and the camming` portion 17 form a` cam means for axially reciprocating the disc 18 during rotation of thelatter. The cam disc 1Sris integral with a projection 19 of substantially rectangular shape which extendsinto a correspondingly shaped slot in they lend portion 14 of the` drive shaft 3, so that the projection `19 connects disc`18 to the drive shaft 3 for rotation therewith while allowing the cam disc 18 to reciprocate axially. As is apparent particularly from Fig. 2 the outer ends of the projection 19 engage thev inner periphery ofthe adjusting ring 15 so that the ,latter centers the projection 19 and disc 18.

The projection 19 is formed with a cutout ofT-shaped configuration extending upwardly, from its bottom edge, as viewed in Fig. 2, and an end portion ofl T-shaped cross section of the piston 5 extends into this T-shaped cutout so that in this way the piston 5 is connected to the projection 19 and disc 18 for reciprocating movement therewith. Thus, the elementslS, V16,17, 18 and 19 form a transmission means. cooperating ywith the drive Ashaft 3 and the piston 5 for reciprocating the latter during rotation of the drive shaft.

The injection pump housing 1 has an open top which is 'closed by the pumpbody 21 which is formed with a cylindrical bore coaxial with the drive shaft 3 and slidably receiving the injection pump piston 22. The bottom endof the piston 22, as viewed in'Fig. l, extends into a recess formed in the top face of the disc 18 and isconnected to the disc 18 for rotation and axial reciprocation therewith by a pin 23 which extends transversely through the piston 22 into cutouts in the top face of the disc 18 which correspond in shape to the free ends of the pin 23 so that the latter together with the piston 22 are constrained to rotate with the disc 18. Axial movement of pin 23 and piston 22 with respect to disc 18 is prevented by a washer 24 engaging the top face of the pin 23, as viewed in Fig. 1, and also engaging a snap ring 25 located in an inner annular groove formed in an upwardly extending annular projection of the disc 18. The injection pump piston 22 is axially bored throughout its entire length and is closed at its end connected to the pin 23 by a stepped pin 27 having an elongated portion extending along the axis of the piston 22 and surrounded by a coil spring 28 which rests at one end against the shoulder intermediate the ends of the stepped pin 27 and at its opposite end against a valve member 29 which is pressed by the spring 28 against a valve seat 30 formed by an inwardly extending annular portion in the interior of the pump piston 22. The valve member 29 has a stem which extends upwardly to a guide fixed to this stem and extending across the interior of the piston 22 into slidable engagement with the inner surface thereof. This guide is, for example, in the form of radially extending fins and does not in any way prevent communication between the valve 29 and the working chamber 31 of the injection pump. In the illustrated closed position of the valve where valve member 29 engages the seat 30, the valve separates the chamber 31 from the chamber 32 in the interior of the piston 22 beneath the valve 29, as viewed in Fig. 1. A plug 33 threaded into the pump body 21 closes the chamber 31 from the outer atmosphere. The wall of the piston 22 is formed just above the valve seat with four openings 34 which are displaced from each other by 90, and below the valve seat 30 the piston 22 is formed. with an opening 35 passing through the wall thereof. The openings 34 act as suction openings and cooperate with an inlet passage 36 which communicates with an inlet opening 37 and which is traversed by a throttling pin 38 slidable in a suitable bore of the pump body 21 and 'formed with an annular groove 39 which overlaps the passage 36 to a predetermined extent, as will be pointed out below.

The opening 35 in the wall of the pump piston 22 acts as a pressure discharge opening and cooperates with four discharge passages 40 formed in the pump body 21, only one of these passages 40 being shown in the drawing. These four passages 40 all communicate in a common plane with the bore in-which the piston 22 slides, and the passages 40 are spaced from each other by 90 at the ends thereof which meet the cylindrical bore which accommodates the piston 22. The passages 40 lead respectively to the outlets 41 which are connected to conduits leading to the several cylinders of the engine, respectively.

A spring 42 is coiled about the piston 22, engages with one end the cam disc 18, and engages with its oppolsite end the inner race 43 of a ball bearing 44, so that the spring 42 turns with the cam disc 18 and at the same time maintains the camming portions 17 in operative engagement with the rollers 16.

The adjusting ring 15, which forms part of the timing mechanism controlling the moments when fuel is injected into the several cylinders, is formed with a transverse bore which receives a pin 45 having an enlarged head 46 formed with opposed at side faces vwhich slidably engaged the opposite side faces of a slot 47 formed in an extension 49 of a pressure responsive member 48 (Fig. 3). It will be noted that the slot 47 is inclined to the axis of the member 48. The elongated portion 49 of member 48 is flattened at opposite side faces, and the member 48 itself is in the form of a hollow piston slidable in a bore 5t) of the housing 1. It will be noted that the piston 48 slides along an axis parallel to that o f the drive shaft 3. The bore Si) communicates with the interior 12 of the housing 1, so that the piston 48 is responsive to pressure Within the housing 1. The pressure of fuel in the interior 12 of the housing acts on the piston 48, and this pressure acting on the piston 48 is opposed by a spring 51 extending into the piston 48 and abutting against a plug 52 which closes the bore 50. The piston 48 has suflicient clearance in the bore 50 to allow fuel to move along the piston 48 to the bore 54 which communicates with the suction side of the fuel supply pump formed by the piston 5 and the cylindrical bore 4 of the drive shaft 3.

As was pointed out above the drive shaft 3 is integral with a gear 55. This gear 55 meshes with a gear 56 carried by a sleeve 57 through which a governor shaft 58 extends, this shaft 58 being parallel to the drive shaft 3 and being tixedly carried by a governor housing portion 59 which is fixed to the housing 1 in such a way that the axes of piston 48, drive shaft 3 and governor shaft 58 all are located in a common plane.

The sleeve 57 fixedly carries at opposite sides thereof four pairs of outwardly extending tins 60, respectively, and between each pair of tins 60 is located a ball 61 which acts as a flyweight of the governor. The ball members 61 act on the frusto-conical inner surface of the annular governor member 62 which is guided by the governor shaft 58 for movement axially along the latter. As is apparent from Fig. 1 with iucreasing speed of rotation of the gear 56 the ball members 61 will move outwardly away from the axis of shaft 58 to raise the annular governor member 62 along the shaft 58, as viewed in Fig. l. A spring 63 is coiled about the shaft 58 and bears at one end against member 62 to maintain the latter in engagement with the ball members 61. The spring 63 bears at its opposite end against an outwardly extending annular flange of a sleeve 64 slidable along the shaft 58 which extends through the sleeve 64. The top face of the sleeve 64 engages a lever 65 which is fixed to a shaft 66 extending from the exterior of housing 59 into the latter and turnably supported by the housing 59. Of course, those portions of the housing 59 which receive shaft 66 as well as shaft 58 are sealed in a lluidtight manner to prevent leakage of fuel from the interior 72 of housing 59 which communicates with the interior 12 of housing 1. A lever 67 is fixed to a portion of shaft 66 which is located outside of the housing 59, and this lever 67 is located between a pair of adjustable stops 68 and 69 carried by projections of the housing 59, respectively. The lever 67 serves to adjust the stress of the spring 63 and in this way serves to set the governor for a particular engine speed. Any suitable known control linkage is connected to the lever 67. The governor member 62 is formed with an outer annular groove 70 to provide the member 62 with an outwardly extending annular flange which extends into an annular groove located adjacent the bottom end of throttling pin 38, this bottom end of throttling pin 35 extending into the groove 70, in the manner indicated in Fig. 1, so that the pin 38 participates in the axial movement of the governor member 62. This axial movement of governor member 62 upwardly from the position shown in Fig. l is limited by a snap ring 71 located in an annular groove formed in shaft 58.

The housing 59 is formed with a fuel outlet opening 73 which communicates, as shown schematically in Fig. l,

' with a conduit 74 leading to the inlet opening 37 of the injection pump. The conduit 74 has a filter 75 built into the same, and the filter 7S communicates with an overow valve 76 which in turn communicates through a suitable conduit with the fuel tank, so that excess fuel delivered by the fuel supply pump to the conduit 74 will pass through the overflow valve 76 back to the fuel tank.

The above described structure operates in the following manner:

Upon rotation of the drive shaft 3 the cam disc 18 @lso rotates and is simultaneously reciprocated axially by fpress'ure. f ings V7 and 8 `are "properly related `to 'rollers l16 and A'cumming portions 17 so'that` during the vsuctionstrokes'of cooperation between lthe `rollers 16 and camming ,portions 17. The piston S participates `in the' axialfreciprocation 'of the cam disc 18. The vpiston 5 moves through its suction strokes when it 'moves upwardly, as viewed in passage 6, one' of the inlet openings 7,-andgr'oove 9 'and "inlet'1tl- Duringeachpressure'stroke the piston forces vfuel out of cylinder 4 through the passage 6 and one of theroutlet openingsS into 'the interior 12 of the housing, this interior 12 thusactingfas areservoir for fuel under Of course, the angular positions of theopenthe piston 5 the passage 6 communicates with the open ings 7 Vand Vnot with 'the openings 8 while during the pressure strokes of the piston 5 the passage 6 communi- Cates with the openings'S andnotwiththe openings 7. Thus, fuel under pressure -is'l'ocat'edin thehinterior 12 of housing 1 laswell asin the interior 72 ofthe governor "housing 59. The pressure responsive piston member-48 Aassumes a'p'osition determinedby"thepressure of the fuel, andthe axial shifting of member 48 will` be transmitted through slot 47 and'pin '45 tothe adjusting ring 15 to adjust the angular position thereof and thus adjust the van'gular position of the rollers 16 so that'the latter engage the cumming portions 17l at a 'particular time which isautomatically regulated in this marmer.V Thus, ele

"ments 48, 45 and 15 form a'timer for the injection pump.

Theffuelows from the interior 12 of housing 1 into the Yinterior 72- of housing 59Y and fromthe `latter to the 'conduit' 74 andlter 75 and'nally to the inlet 37 of the injection pump. The excess fuel flows from the overfflow' valve 76`back to the Vunillustrated fuel tank which communicates "through aconduit (not shown) With the inlet of the fuel supply pump.

fFrom"the`inlet opening 37 of vthe injection pump the 'fuelgows during the suction strokes of piston 22 through the passage Iand suction openings 34 into the chamber 31. During thepresSure lstrokes of thev piston 22 the v "openings/Mare out of register with the passageY 36 and the p1'essure`-str'ok`es of the Vpiston 22 cause the fuel trapped in the chamber" 3110 open valve 29 'against the influence :of spring 2S, the fuel `then moving by the valve'member l29;"'in`to the chamber 32 of 'the piston 22.v From the chamber 32 the fueliiows through the pressure outlet opening 35 and the particular discharge passage 40` in *register therewith to one ofthe outlets 41 and from the latter to a'particular `cylinder of ythe engine.

'n I fthe speed of rotation of theengine increases so that the'speed of rotationv of 'drive shaft 30 which is 'rdrivenwby theengine alsowi'ncreases, then the amount of fuel supplied by the fuelsupply pump 3 5 in al'given unit oftime' is correspondingly` greater. :inasmuch as ove'row valve 76 acts also as a throttle, 'the pressure of the fuel inthe interiorportions 12 and 72 of housings 1 and'591, respectivelyylincreases and thus shifts the pressure responsive piston itiV downwardly, as viewed in Fig.

l. This downward movement of the piston 48 against the influence of spring 51 results in a turning of the ring 15 because oi' the cooperation of the head 46 of pin vS5 with the inclined slot 47, and as a result the supply of fuel by the injection pump and thus the instants when the fuel is injected'into the several cylinders of the engine takes place earlier with respect to the positions of the pistons ofthe engine.

Il? the speetl of the engine increases because of a `.reduction in the load on' the engine, for example, while l. the position lever 67 remains unchanged, then the yweight members 61 move outwardly from the axis of shaft 5S and raise the annular governor member 62 "against the influence of the spring 63. The upward movement of member 62, as viewed in Fig. l, results in upward movement ofthe throttling pin 38, and as a result ys theannularfgroovel 39 of the throttlingpin' overlaps the -passage 36 to a smallerextent so that the-flow of fuelalong the passage 36 to the interior of the injection .small space and because of the simple construction of its components is very-inexpensive tofmanufacture.

The governor together with its housing 59 forms a subassembly `which can be manufactured separately and then joined to the housing 1. This is of particular advantage because it is in this way possible toexchange one governor subassemblyfor another Without disturbing the remainder of the structure. Also, the pump body 21 together with piston 22, cam disc ivandspring 42 as well as throttling pin 33 form a separate subassembly joined to the housing-1 and capable, when necessary, Aof being easily exchanged for another subassembly.

As is `apparent from Fig. A3, the axial shifting of the l pressure responsive piston 4S will turn-the adjusting ring 15 through a relatively small angle, and the left portion of the ring 1S, as viewed in Fig. 1, is cut away through a sufficient distance to allowthe governor member 62 to rotate freely at all angular positions of the ring 15.

lt'will be understood Vthat .each of the elements described above, or two or more-together, may also nd a useful application in other types of combined injection pumps and fuel supply pumps therefor differing from the types described above.

While the invention has been illustrated and described as embodied in assemblies including an injection pump, a fuel supply pump, a timer and ya governor, it is not intended to belimited to the details shown, since various modifications and structural changes may be made without departing-in anyway from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the `gist of the present invention that others can by applying current knowledge readily adapt it for various applications with-out omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, vsuch adaptationsshould and are intendedfto be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

l. In a pump, in combination, support means; a drive shaft turnably carried by said support means and being formed with an axially extending bore which acts as the cylinder of the pump; a piston slidable in said bore; and transmissionmeans cooperating with said drive shaft and piston for reciprocating the latter in said bore during rotation of said drive shaft.

2. In a pump, in combination, support means; a drive shaft turnahly carried by said support means and being formed with an axially extending bore which acts as a cylinder of the pump; a piston slidable in said bore; cam means and follower means, one of said means being connected to said drive shaft for rotation therewith and for axial movement with respect to the same and the other of said means cooperating with said one means for reciprocating tie latter axially during rotation of said one means with said drive shaft; and means connecting said one means and piston together for axial movement toigether, sothat said piston reciprocates in said bore.

ISV

cylinder of the pump; a piston slidable in said bore; transmission means cooperating with said drive shaft and piston for reciprocating the latter in said bore during rotation of said drive shaft; and means controlled by rotation of said drive shaft with respect to said support means for regulating the flow of liquid into and the discharge of liquid from said bore.

4. In a pump, in combination, a bearing sleeve having a pair of wall portions located in a common plane normal to the sleeve axis formed respectively with an inlet opening and an outlet opening; a drive shaft extending through and turn-ably supported by said sleeve and being formed with an axially extending bore which acts as the cylinder of the pump, and said drive shaft being formed with a passage communicating with said bore and extending through a Wall portion of said drive shaft, said passage being located in said plane so that during rotation of said drive shaft said bore communicates through said passage with said inlet opening in one angular position of said drive shaft and with said outlet opening in another angular position of said drive shaft; a piston slidable in said bore; and transmission means cooperating with said drive shaft and piston for reciprocating the latter during rotation of said drive shaft and for moving said piston along its suction stroke when said passage communicates with said inlet opening and along its pressure stroke when said passage communicates with said outlet opening.

5. In an assembly which includes an injection pump, a governor, and a timer for the injection pump, in combination, support means; an injection pump drive shaft rotatably carried by said support means; a governor shaft carried by said support means for shiftably supporting a governor member which shifts along said governor shaft in response to a change in the speed of rotation of said injection pump drive shaft; and a fuel pressure responsive member shiftably carried by said support means for movement along a given axis to regulate a timer for the injection pump, said latter axis and the axes of said drive shaft and governor shaft all being located in a A common plane, and all being parallel to each other.

6. In a pump, in combination, a bearing sleeve formed with an inlet opening and an outlet opening extending through said sleeve transversely to the axis thereof; a drive shaft extending through and turnably supported by said sleeve and being formed with an axially extending bore which acts as a cylinder of the pump, and said drive shaft being formed with passage means communicating with said bore and extending to the exterior of said drive shaft, said passage means communicating with said inlet opening in one angular position of said drive shaft and with said outlet opening in another angular position of said drive shaft so that during rotation of said drive shaft the bore therein alternately communicates with said inlet opening and said outlet opening; a piston slidable in said bore; and transmission means cooperating with said drive shaft and piston for reciprocating the latter during rotation of said drive shaft and for moving said piston along its suction stroke when said passage means communicates with said inlet opening and along its pressure stroke when said passage means communicates with said outlet opening.

7. In a pump arrangement, in combination, a support; a drive shaft turnably carried by said support and being formed with a bore acting as a pump cylinder and extending in axial direction away from an end face of said drive shaft; cylinder means arranged co-axially with said drive shaft beyond said end face thereof; piston means arranged in said cylinder means, said cylinder means and piston means being slidable relative to each other in axial direction thereof and one of said means being carried by said support; a piston slidable in said bore and connected to the other of said means for simultaneous movement in axial direction so that said piston and said other means extend in opposite direction and form one reciprocatable unit; and means for reciprocating said unit during rotation of said drive shaft.

8. In a pump arrangement, in combination, a support; a drive shaft turnably carried by said support and being formed with a bore acting as a pump cylinder and extending in axial direction away from an end face of said drive shaft; cylinder means arranged co-axially with said drive shaft beyond said end face thereof; piston means arranged in said cylinder means, said cylinder means and piston means being slidable relative to each other in axial direction thereof and one of said means being carried by said support; a piston slidable in said'bore and connected to the other of said means for simultaneous movement in axial direction so that said piston and said other means extend in opposite direction and form one reciprocatable unit; and means actuated by rotation of said drive shaft for reciprocating said unit during rotation of said drive shaft.

9. In a pump arrangement, in combination, a support; a drive shaft turnably carried by said support and being formed with a bore acting as a pump cylinder and extending in axial direction away from an end face of said drive shaft; cylinder means arranged co-axially with said drive shaft beyond said end face thereof; piston means arranged in said cylinder means, said cylinder means and piston means being slidable relative to each other in axial direction thereof and said cylinder means being carried by said support; a piston slidable in said bore and connected to said piston means for simultaneous movement in axial direction so that said piston and said piston means extend in opposite direction and form one reciprocatable unit; and means actuated by rotation of said drive shaft for reciprocating said unit during rotation of said drive shaft.

.10. In a pump arrangement, in combination, a support; a drive shaft turnably carried by said support and being formed with a bore acting as a pump cylinder and extending in axial direction away from an end face of said drive shaft; cylinder means arranged co-axially with said drive shaft beyond said end face thereof; piston means arranged in said cylinder means, said cylinder means and piston means being slidable relative to each other in axial direction thereof and said cylinder means being carried by said support; a piston slidable in said bore and connected to said piston means for simultaneous movement in axial direction so that said piston and said piston means extend in opposite directions and form one reciprocatable unit; and means actuated by rotation of said drive shaft and located between said piston and said piston means for reciprocating said unit during rotation of said drive shaft.

1l. In a pump arrangement, in combination, a support; a drive shaft turnably carried by said support and being formed with a bore acting as a pump cylinder and extending in axial direction away from an end face of said drive shaft; cylinder means arranged co-axially with said drive shaft beyond said end face thereof; piston means arranged in said cylinder means, said cylinder means and piston means being slidable relative to each other in axial direction thereof and one of said means being carried by said support; a piston slidable in said bore and connected to the other of said means for simultaneous movement in axial direction so that said piston and said other means extend in opposite direction and form one reciprocatable unit; means for reciprocating said unit during ro-v tation of said drive shaft; and means controlled by rotation of said drive shaft for regulating the ow of liquid into and the discharge of liquid from said bore.

12. In a combined injection pump and supply pump therefor, in combination, a support; a bearing sleeve tixed to said support and being formed with an inlet opening and an outlet opening extending through said sleeve transversely to the axis thereof; a drive shaft extending through and turnably supported by said sleeve and being formed with a bore acting as cylinder of the supply pump and extending in axial direction away from an end face of said drive shaft, said drive shaft being formed with passage means communicating with said bore and extending to the exterior of said drive shaft, said passage means communicating with said inlet opening in one angular position of said drive shaft and with said outlet opening n another angular position of said drive shaft so that during rotation of said drive shaft the bore therein alternately communicates with said inlet opening and said outlet opening; cylinder means carried by said support and being arranged co-axially with said drive shaft beyond said end face thereof; piston means arranged in said cylinder means and being slidable relative thereto in axial direction thereof; a piston slidable in said bore and connected to said piston means for simultaneous movement in axial direction so that said piston and said piston means extend in opposite directions and form one reciprocatable unit; and means cooperating with said drive shaft for reciprocating said unit during rotation of said drive shaft and for moving said piston along its suction stroke when said passage means communicates with said inlet opening and along its pressure stroke when said passage means communicates with said outlet opening.

References Cited in the file of this patent UNITED STATES PATENTS 2,618,252 Knudsen Nov. 18, 1952 2,624,327 Hogeman Jan. 6, 1953 2,641,238 Roosa `lune 9, 1953 2,660,992 Roosa Dec. 1, 1953 2,672,817 Friedlander Mar. 23, 1954 2,784,670 High et a1. Mar. 12, 1957 

